Method of hobbing gears



INVENTOR. 02:15 I. Sid bias. ?flw; WW5. W

. ATTORNEY$ 5 Sheets-Sheet 1 Sept. 1, 1942. o. E. STAPLES METHOD OF HOBBING GEARS Original Filed Feb. 24, 1937 Sept. 1, 1942. o. E. STAPLES Re. 22,173

METEOD OF HOBBING GEARS Original Filed Feb. 24, 1937 3 Sheets-Sheet 2 ATTORNEY? o. E. STAPLES Re. 22,173

METHOD OF HOBBING GEARS Original Filed Feb. 24, 19 7 3 Sheets-Sheet 3 INVENTOR.

ATTORNEY5 Reissued Sept. 1, 1942 2 METHOD OF HOBBING GEARS Otis E. Staples, Euclid, Ohio, assignor to The Cleveland Hobbing Machine Company, Cleveland, Ohio, a corporation of Ohio Original No. 2,211,611, dated August 13, 1940, Se-

rial No. 127,432, February 24, 1937. Application for reissue September 18, 1941, Serial No.

2 Claims.

The present invention relates to gear cutting and more particularly to a method or hobbing gears, splines, and the like.

An object of the present invention is the provision of a novel and improved method of hobbing gears, etc., which will produce articles of greater accuracy in less time than has heretofore been possible.

Another object of the present invention is the provision of a novel and improved method of hobbing wherein the hob is so rotated and translated relative to the work blank that the teeth out from the periphery of the blank toward the center thereof.

The present invention resides in producing certain relative movements between the cutter and the work blank, and in certain details of construction and combinations and arrangements of parts, and further objects and advantages thereof will be apparent to those skilled in the art to which it relates from the following description of the method and the preferred embodiment of a machine for carrying out the method, described with reference to the accompanying drawings forming a part of this specification, in which similar reference characters designate corresponding parts throughout the several views, and in which Fig. 1. is a perspective View of a hobbing machine embodying the present invention;

Fig. 2 is a vertical section through the machine shown in Fig. 1 .on the center line thereof,

with the work head dropped to its lower position, the hob head rotated to a vertical position, and the hob'and work arbor omitted;

Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a section on the line 4-4 of Fig. 2;

Fig. 5' is a wiring diagram of the electrical circuits of the machine, and

Fig. 6 is an enlarged view showing the hob and the work blank in operating engagement.

According to the provisions of the present method a work blank is moved vertically while a hob is rotated in cutting relation thereto and in such a manner that the cutting thrust produced by the hob is in the direction of the feed movement imparted to the work. In other words, the hob is rotated in such a manner that the teeth thereof cut from the outside of the blank towards the center thereof, while the work is moved axially and parallel to or substantially parallel to the gravitation of force acting thereon or on the work head which carries the work. The preferred machine for practicing the method of the present invention will now be described although it is to be understood that the invention can be applied to machines of different construction.

The machine illustrated is of generally vertical construction, and the bed thereof, designated in general by the reference character A, which also serves as a sump for the cutting fluid, etc., is made rectangular, permitting a number of machines to be readily ganged close together, synchronized and taken care of by a single operator. The frame of the machine, designated in general by the reference character B, is of heavy channel construction, providing maximum rigidity with minimum weight, and is bolted or otherwise securely fixed to the bed A.

The work head, designated in general by the reference character C, comprises a frame I0, slidably supported on vertically spaced ways H and I2 formed on the frame B at the top and bottom thereof, respectively. The work head is held in engagement with the lower ways [2 by members I3, see Fig. 3, bolted to the rear side of the work head frame 10 and projecting to the rear of the overhanging portions on the Ways l2. Adjustable tapered gibs I4 interposed between the members I3 and the ways II are provided for the purpose of taking up the wear, etc. An adjustable gib I5 interposed between a rib on the rear of the work head frame and the right hand way prevents any side movement of the work head relative to the ways l2. The upper part of the work head 0 is maintained in engagement with the ways H in a manner similar to that in which the lower part of the work head is maintained in engagement with the lower ways I2. This construction provides a rigid support for the work, free from vibration, chatter, etc.

The work blank designated in general by the reference character W, is non-rotatably secured in any convenient manner, to a work arbor ll supported between a tail center 18 carried by a tail stock I9 slidably supported on the ways 20 formed integral with the work head frame In, and a chuck 2'l fixed to the upper end of a work spindle 22 rotatably supported in the work head by anti-friction bearings 23. The tail stock I9 is adapted to be moved along the ways 20 by an operating handle 25 pivotally connected to the outer end of a member 26 rotatably supported in the tail stock and provided at its inner end with a gear, not shown, continually in mesh with a rack 21 secured to the work head frame H1. The

ries a gear 53 fixed thereto. eratively connected to a gear 54 fixed toa horitail stock along the ways. The work blank W may be non-rotatably secured to this work arbor in any convenient manner.

The work spindle 22 is driven from an electric motor supported on an adjustable platform in a recess in the frame B and connected to the main drive shaft 3| of the machine by a fleible drive connection designated in general by the reference character 32. The rear end of the main'drive shaft 3| is rotatably supported in a boss 33 formed integral with the frame 13, and

the front end thereof is supported in .a member 35 fixed to the frame B, through the medium of a bevel gear 36 splined thereto, the hub of which gear is rotatably supported in an aperture 31 in the member 35 by anti-friction bearings 38.

The bevel gear 36 previously referred to is continuously in mesh with a bevel gear 40 fixed to the upper end of a vertically positioned spline shaft 4| the upper end of which is rotatably supported in the member 35. The lower end of the spline shaft 4 extends into an oil recess 43 in the work head C and has a splined connection with a bevel gear 44 provided with an elongated hub rotatably supported in a rearwardly extending portion 46 of the work head frame. The bevel gear 44' is continuously in mesh with a bevel gear 48 fixed. to the rear end of a horizontal shaft 49, the rear end of which shaft is rotatably supported in the Work head frame by anti-friction bearings 50.. The front end of the shaft 49 is rotatably supported in a partition 5| in th work head frame by anti-friction bearings 52, and car- The gear 53 is opzontal, shaft 55 through change gears 56 and 51 in mesh with gears 53 and 54, respectively. The change gears 56 and 51 rotate in unison and are rotatably supported on a sleeve surrounding a bolt 58, which bolt is adjustably supported in a T-slot in a bracket 50. The bracket 59 is rotatably supported coaxial with the shaft 49, andis adapted to be secured in any adjusted-position by suitable means not shown. The shaft. 55 is operatively connected to the work spindle 22 through a worm and worm wheel 60 and GI, respectively, the former of which is fixed .to the shaft 55 and the latter to the spindle 22.

" In order to provide means for taking up wear and lost motion between the worm 60 and worm --wheel 6| the shaft 55 is rotatably supported in a sleeve member 62 which, in turn, is rotatably supported in the frame of the work head eccentric with reference to the axis of the shaft 55. The reduced rear end of the member 62 is rotatably supported in a recess in the work head frame, and the front end thereof is provided with a flange 63 rotatably supported in the partition 5|. The member 62 is rotated so as to move the worm 60 into or toward the worm wheel 6| by a member 64 threaded into an aperture in the partition 5|, and provided with a reduced end portion which abuts a fiat surface on the flange 63. Cap screws 65 projecting through arcuate slots in the flange 63 and having threaded engagement with the partition 5| provide means for securing the sleeve member 62 in any adjusted position.

The tool head, designated in general by the reference character D, comprises a member 10 slidably supported on horizontal ways formed integral with the frame B intermediate the vertically spaced ways H and I2 and a member 12 rotatably supported by the member 10 coaxial with the main drive shaft 3|., A tool spindle I3 which is rotatably supported in the member [2 by suitable anti-friction bearings is driven from the main drive shaft 3| through miter gears 14 and 15, the former of which is provided with an elongated hub splined to the front end of the main drive shaft 3| and rotatably supported in a rearwardly extending boss I6 formed integral with the member 12. Miter gear 15 is fixed to the lower end of a stud shaft 11 rotatably supported in the member 12, the upper end of which carries a spiral pinion 18 in mesh with a spiral gear 19 fixed to the tool spindle 13. The hub designated generally by the reference character H is carried by a hob arbor B0 fixed at its upper end, as viewed in Fig. 2, to the tool spindle 13. The lower end of the hob arbor is rotatably supported in a bracket 0| bolted to the member 12. The upper end of the tool spindle is provided with a flywheel B5 fixed thereto. The member 12 is rotatably supported by the member 10 by the engagement of the boss I6 in a cylindrical aperture in the front wall of the member 10. Bolts 86, the heads of which engage in a circular T-slot 81 are provided for securing the member 12 in any adjusted angular position. The construction just described permits the axis of the hob to be adjusted about the'axis of the main drive shaft 3|, and a Vernier scale 88 permits the hob to be accurately and quickly set at any desired angle.

Movement of the tool head D along the ways II to move the hob toward or from the work is effected upon the rotation of a shaft 90 rotatably supported in the frame B and provided with a worm 9| fixed thereto which worm is continuously in mesh with a rack 92 secured to the underside of the member 10. The shaft 90 is provided with a square end to facilitate turning the same and a graduated dial 93 to facilitate setting of the hob.- The tool headis adapted to be clamped to the way 1| in any adjusted position by bolts 34, if desired. The member 70 has a telescopic connection with the boss-like member 35, which prevents the entrance of chips, etc.,- into the interior of the tool head, while permitting movement thereof along the ways 1|. I

- In the machine. shown the downward-movement of the work head 0 which movementcarries. thework blank past the tool, isteffected by the weight of the work head but is controlled through the medium of a lead screw |00 rotatably supported in the work head B, and having threaded engagement with a nut |0| rotatably supported in a bracket I02 bolted. or otherwise secured to the base A. Linear movement of the screw I00 and the nut |0| relative to the work head frame l0 and the bracket I02, respectively, is prevented by anti-friction thrust bearings I05 and I06 interposed between the lead screw I00 and the work head frame |0,and the nut |0| and the bracket I02, respectively. The leadscrew l00 is driven in predetermined timed. relation to the rotation of the workv and toolspindle, to lower the Work head B at the desired feed ,rate,.from a gear I01 fixed to the extreme outer. end of the shaft 55, which gear is operatively connectedv to a gear J08 fixed to the front end of .a horizontal shaft I09 through the medium of change gears ||0 andl II in mesh with the gears I01 andv I08, respectively. The change gears H0 and IN are rotatably supportedon a .stud shaft ||2-v adjustably secured in an elongated slot in a bracket 3, rotatably supported coaxial with the shaft I09 and adapted to be secured in any adjusted position by means of a'bolt ||4 threaded onto a projection, I I5 formed on the partition 5|. The bolt 4 projects throughanarcuate slot in the bracket H3. The shaft I09 which is rotatably supported in the frame I and the partition -I by anti-friction bearings has a worm II6 fixed thereto, in mesh with a worm wheel II1 fixed to the upper end of the lead screw I00.

A rapid traverse movement is imparted to the work head C to quickly bring the work down to the cutter, or to quickly return the work head to its starting position, by a reversible motor I supported on the bed A within the frame B, and operatively connected to the nut I 0 I through the medium of a shaft I2I, rotatably supported in suitable bearings in the bracket I02, and connected to the armature shaft of the motor I20 by a suitable coupling. The shaft I2I has keyed thereto a Worm I22 in mesh with a worm wheel I23 formed about the circumference of the nut MI. The worm I22 and worm wheel I23 are of the self-locking type which prevents rotation of the nut IOI with reference to the lead screw I00 while the motor I20 is at rest during the feeding movement of the work head.

The work head frame I0 is divided into two compartments by the partition 5|, both of which compartments are adapted to be filled with oil M to a suitable level for the lubrication of the various parts housed within the compartments. All the gears, etc., in the work head are enclosed within the same, which prevents the entrance of chips and dirt, etc., thereinto. A telescopic guard I24 prevents the accumulation of chips, etc., on the ways I2. Cutting fluid is supplied to the tool by a pump I25 driven from the motor through a flexible drive connection I26. Since the motor 30 is energized only during the cutting operation the cutting fluid is supplied merely as needed. The pump I25, like the motor 30, is supported on an adjustable base in a recess in the frame B.

The motors 30 and I20 preferably are three phase alternating current motors and the motor I20 is reversible. The operation of the motors is under the control of upper and lower limit switches I30 and I3I, respectively, and a startstop push button switch I32, both the start and stop buttons I33 and I34, respectively, of which are provided with ferrules adapted to limit the movement thereof. Both the'limit switches and the start-stop push button switch are well known in the art and per se do not form a part of the present invention and may be of any conventional construction. The start button I33 is normally in the out position, i. e., the position shown in the wiring diagram, but may be set in the neutral position by the ferrule I35 associated therewith, and the stop button I34, which is normally closed, may be set in the open position by the ferrule I36 associated with it. The limit switches I30 and I3I are operated and controlled by adjustable stops I31, I38 and I39, carried by the Work head 0. The stops I31 and I38 engage the arms I40 and MI of a bell crank lever on the limit switch I30 to actuate said switch, and the stop I39 engages the arms I42 and I43 of a bell crank lever on the limit switch I3I to actuate the same.

The motor 30 is connected to and from the supply lines L1, L2, L3 through the medium of a solenoid operated circuit breaker panel I45; the operating solenoid and holding-in circuit of which are indicated at c and 0, respectively. The motor I20 is connected to and from the supply lines through the reversible circuit breaker panel I46, the operating solenoids and their respective holding-in circuits of which are designated as u, u and d, d. The reference character u designates the solenoid which closes the circuit to the motor I20 to operate the same in a direction to raise the Work head C, and the solenoid which closes the circuit to motor I20 to lower the work head is designated by the reference character d. The leads to the motor 30 are designated T1, T2, T3, and to the motor I20 as T1, T2, T3. The reference character I41 designates a contact relay. The panels I45 and I46 are enclosed in the head of the frame B behind the covers I48 on opposite sides of the frame.

The operation of the machine is as follows: With the machine at rest and a work head in the upper position, the electrical circuit is as shown in the wiring diagram. Assuming that a. work blank has been secured in position between the work spindle chuck and the tail center, the start button I33 is pressed by the operator, closing the circuit to the contact relay I 41 which, in turn, closes the circuit to the solenoid d, energizing the motor I20. The motor I20 in turn rotates the nut IOI at a high speed to quickly lower the work head under its own weight and bring the work down to the hob. Upon release of the start button I33 the circuit relay I41 is closed through the holding-in circuit d which is now energized. Thereafter the relay I41 maintains its own circuit. The stop I39 is so positioned that it engages the upstanding arm I42 of the limit switch I3I and moves the contact arm to its lower position, see Fig. 5, just prior to the engagement of the work with the hob, opening the circuit to solenoid d and closing the circuit to solenoid 0, through the contacts of relay I41, stopping the motor I20 and starting the motor 30. The holding-in circuit 0' maintains the circuit to the motor 30 until the work has traveled down past the hob and the cutting operation has been completed, at which time the stop I31 engages the arm I40 and trips the limit switch I30, opening the circuit to the motor 30 and resetting the circuit to the solenoid u so that the motor I20 will be energized to quickly raise the work head C to its starting position when the start button I33 is again pressed.

The work head C remains at rest in the lower position until the finished blank has been removed, after which the start button I33 is pressed by the operator to raise the work head. As the work head C moves up, the stop I39 engages the arm I43 and returns the limit switch I3I to its initial or starting position without interrupting the circuit to the motor I20. As the work head 0 approaches its upper limit of movement, the stop I38 engages the lever I4I, returning the limit switch I30 to its starting or initial position, and interrupting the circuit to the motor I20. After a new blank has been positioned on the work head, the cycle of operations is repeated. Stationary pins I50 fixed to the work head frame I0 limit the movement or adjustment of the stops I31 and I38 so that it is impossible for the work head C to be accidentally moved off of the way, etc. The machine may be stopped at any time during an operation by merely pressing the stop button I34, after which the machine can only be started by pressing the start button I33.

If desired, the stop button I34 can be set in an open position by turning the ferrule I36, in which event the machine will not start upon movement of the start button I33. This construction is particularly important when making repairs on the machine, etc. The start button I33 can likewise be set in a neutral position by L motor 30.

turning the ferrule I35, in which event the work head 0 will stop at the end of its traverse down movement without automatically starting the This operation is followed in setting up the machine and where the tool is making a second cut on a blank and it is desired to line up the same.

The direction of rotation of the motor 30 and the gearing, "etc., is such that the rotation of the hob is as indicated by the arrow 1: in Fig.- 6, while the vertical feed movement of the work is in the direction of the arrow y, that is axially of the work. In otherv words, the spindle moved to effect the feed is moved in the direction of its axis and in line with the action of gravity. From the foregoing it will be apparent that each tooth of the hob cuts from the outside of the blank towards the center thereof and that the' heavy part of. the cut occurs as the tooth of the hob enters the work. While the size of the chips shown in Fig. 6 has been exaggerated somewhat,

understood that the direction of feed, etc., may

be reversed. In the machine shown the weight of the work head is adequate toprevent backlash when the feed is in an upwardly direction, but even so it is advantageous to operate it in the preferred manner, since when operated in this manner the chips fall clear of the work and tool more readily and the thrust produced by the cutting action is against the heavy headstock instead of against the relatively light tailstock.

From the foregoing description, it will be apparent that the objects of the present invention heretofore enumerated and others have been accomplished and that a novel and improved method of hobbing has been provided wherein the work blank is moved vertically in the direction of its axis and in line with the gravitation of force exerted thereon in cutting relation to the hob which is rotated in such a manner that the hob cuts from the outside of the blank towards the center.

Having thus described my invention, what I claim is:

1. The method of hobbing which comprises rotating a blank to be out about a vertical axis while moving the same vertically in cutting relation past a hob rotated in timed relation to the rotation of the blank and in such a direction relative to the direction of feed that the hob cuts from the periphery of the blank towards the center with the vertical component of the cutting thrust produced thereby acting upon the work in the direction in which the blank is moving.

2. The method of hobbing which comprises rotating the blank to be cut about a vertical axis while moving the same in a downward direction in cutting relation past a hob rotated in timed relation to the rotation of the blank and in such a direction relative to the direction of feedthat the hob cuts from the periphery of the blank towards the center with the vertical component of the cutting thrust produced thereby acting upon the Work in a direction in which the blank is moved.

OTIS E. STAPLES. 

